Understanding and Addressing Variation in Health Care-Associated Infections After Durable Ventricular Assist Device Therapy: Protocol for a Mixed Methods Study

Mortality following durable left ventricular assist device implantation by timing and type of first infection

OBJECTIVE

Although infections are common after left ventricular assist device implantation, the relationship between timing and type of first infection with regard to mortality is less well understood.

METHODS

The Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support patients receiving a primary left ventricular assist device from April 2012 to May 2017 were included. The primary exposure was defined 3 ways: any infection, timing of first infection (early: ≤90 days; intermediate: 91-180 days; late: >180 days), and type (ventricular assist device specific, ventricular assist device related, non-ventricular assist device). The association between first infection and all-cause mortality was estimated using Cox regression.

RESULTS

The cohort included 12,957 patients at 166 centers (destination therapy: 47.4%, bridge-to-transplant: 41.2%). First infections were most often non-ventricular assist device (54.2%). Rates of first infection were highest in the early interval (10.7/100 person-months). Patients with any infection had a significantly higher adjusted hazard of death (hazard ratio, 2.63; 2.46-2.86). First infection in the intermediate interval was associated with the largest increase in adjusted hazard of death (hazard ratio, 3.26; 2.82-3.78), followed by late (hazard ratio, 3.13; 2.77-3.53) and early intervals (hazard ratio, 2.37; 2.16-2.60). Ventricular assist device-related infections were associated with the largest increase in hazard of death (hazard ratio, 3.02; 2.69-3.40), followed by ventricular assist device specific (hazard ratio, 2.92; 2.57-3.32) and non-ventricular assist device (hazard ratio, 2.42; 2.20-2.65).

CONCLUSIONS

Relative to those without infection, patients with any postimplantation infection had an increased risk of death. Ventricular assist device-related infections and infections occurring in the intermediate interval were associated with the largest increase in risk of death. After left ventricular assist device implantation, infection prevention strategies should target non-ventricular assist device infections in the first 90 days, then shift to surveillance/prevention of driveline infections after 90 days.

Interhospital variability in health care-associated infections and payments after durable ventricular assist device implant among Medicare beneficiaries

OBJECTIVE

The objective of this study was to investigate variations across hospitals in infection rates and associated costs, the latter reflected in 90-day Medicare payments. Despite high rates and expenditures of health care--associated infections associated with durable ventricular assist device implantation, few studies have examined interhospital variation and associated costs.

METHODS

Clinical data on 8688 patients who received primary durable ventricular assist devices from July 2008 to July 2017 from the Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) hospitals (n = 120) were merged with postimplantation 90-day Medicare claims. Terciles of hospital-specific, risk-adjusted infection rates per 100 patient-months were estimated using Intermacs and associated with Medicare payments (among 5440 Medicare beneficiaries). Primary outcomes included infections within 90 days of implantation and Medicare payments.

RESULTS

There were 3982 infections identified among 27.8% (2417/8688) of patients developing an infection. The median (25th, 75th percentile) adjusted incidence of infections (per 100 patient-months) across hospitals was 14.3 (9.3, 19.5) and varied according to hospital (range, 0.0-35.6). Total Medicare payments from implantation to 90 days were 9.0% (absolute difference: $13,652) greater in high versus low infection tercile hospitals (P < .0001). The period between implantation to discharge accounted for 73.1% of the difference in payments during the implantation to 90-day period across terciles.

CONCLUSIONS

Health care--associated infection rates post durable ventricular assist device implantation varied according to hospital and were associated with increased 90-day Medicare expenditures. Interventions targeting preventing infections could improve the value of durable ventricular assist device support from the societal and hospital perspectives.